Tubular pump

ABSTRACT

The invention provides the arrangement of a resilient and flexible tubular element, with shape memory, which contains the product to be metered and which receives an action of limited compression of the walls thereof, in such a way that there is no contact between the internal walls of the opening of the tubular element which propels the product, in such a way that the product supply and discharge are controlled by respective valves situated before and after the compressible tubular metering element.

The present invention relates to a tubular pump which has outstandingfeatures of novelty and inventive step.

In liquid metering technology, for example in pharmaceutical or otherfields, it is necessary to use pumps which can meter various types ofliquid, gel or the like with great precision, while achieving excellentasepsis and operational reliability. Furthermore, the quantities to bemetered in each cycle must be able to be easily varied.

Different types of mechanical pumps are known at present, for examplepiston pumps in which liquid is metered by the positive movement of apiston, combined with a valve system for supplying and dischargingliquid and with different means for varying the quantities metered ineach cycle. Also known are systems in which other types of pump are usedtogether with inlet and outlet control valves, including in some casesstorage receivers situated before the metering conduits.

Said types of pump known at present have a number of drawbacks whichhinder their use and make their practical application more expensive.Firstly, account must be taken of the difficulty in cleaning the pumpand the valves thereof when changing the liquid to be metered, thisbeing an awkward and relatively unsafe task from the point of view ofasepsis. There are also problems of reliability, as the pumps arebasically mechanical pumps, thus implying a large number of parts whichcould suffer damage, wear, etc. Among the drawbacks of pumps which areknown at present, account must also be taken of the inevitable contactbetween the liquid and various materials, in many cases metal materials,which is also disadvantageous for some types of liquid to be metered.

Another type of known pump is the peristaltic pump in which acompression element thoroughly compresses a tubular element which isfull of liquid to be pumped, moving along a variable portion of thetube, thereby causing the positive displacement of the contents of thetube and the pumping action. However, a major disadvantage of thesepumps is the complete mechanical collapse of the tube, which acceleratesthe ageing thereof and detrimentally affects the integrity of themetered product, since in many cases some molecules of the product cansuffer damage due to compression. Further disadvantages of peristalticpumps are the unsatisfactory dose repeatability and the high dependencyof the metered quantity on the precise path of the roller or rollers,since in many cases the final positions are not entirely precise,thereby affecting the repeatability of the dose.

Taking into account the prior art, the inventor has carried out aplurality of tests and investigations to produce a pump which overcomes,at least substantially, the earlier drawbacks. The inventor's researchand tests have resulted in the production of a tubular-type pump whichhas original features and which provides superior quality in terms ofasepsis, constructional simplicity and reliability.

Basically, the new tubular pump is based on the use of a tubular elementmade of resilient material, such as for example rubber, PVC, silicone,etc., for containing liquid which is to be metered and which travels inan intermittent and controlled manner through the tube as a result of anaction of transverse compression thereof, which is converted into apumping of liquid contained in the tube by combination of said action oftransverse compression with a liquid inlet valve which will be closedduring compression and a liquid outlet valve towards the receiver to befilled which will open during compression. When the action ofcompression transverse of the tube is complete and natural recoverythereof has been made possible by its own resilience, the inlet valvewill be open to allow the new liquid to enter and the outlet valve willbe closed to prevent the unchecked discharge of liquid towards thereceivers to be filled. The action of compression preferably takes placebetween a lower surface or planar die and an upper planar rammingmember, in such a way that, for a given tube, the quantity of liquidwill vary with the compression stroke and the length thereof, since,once compressed, it will represent the decrease in volume of the tubefrom its original shape with a circular cross-section to the final shapein which it will adopt the shape of a rectangle with plane parallelsides and ends in the shape of semi-circumferences with diameters equalin size to the smaller side of the rectangle. Given the resilience ofthe tube, recovery of the original shape after each compression cycle,i.e. metering, is ensured.

The precise section of the tube can also be varied by the drawingthereof, which will be a means for varying the quantity of liquidprovided in each compression cycle of the ramming member.

The pump will be able to comprise a plurality of tubular elements forthe simultaneous metering of various lines with an identical ordifferent product, and with likewise variable doses, making it possibleto fill different receiver lines or supply different liquids to the samereceivers of a given container line. The new pump can therefore be usedin a very versatile manner.

The tube can be made of a single part from the initial receiver to thefinal destination; and this makes cleaning the pump very easy and safe.

Excessive stroke values are not required for the pump to operateproperly. On the contrary, one significant feature to take into accountis specifically that the transverse compression level of each tubularelement in the pump will be very moderate and, once the tube isdistorted to a limited extent, this allows for extraordinarily long-termoperation of each tube while maintaining the operational featuresthereof.

One of the applications of the pump according to the present inventionis filling the receivers with cards for clinical analysis in which themicro-receivers of each card will be able to receive the differentproducts in a liquid or gel state in order to fulfil their function.

One example of a pump according to the present invention will comprisethree successive units which have a similar structure and which aresynchronised in their operation, one of them having, for metering, aplanar base for receiving the flexible and resilient tubular element anda compression ramming member, likewise planar, actuated by anyappropriate means, for example hydraulic, pneumatic, electromagneticmeans, etc., in order to compress the tubular element, its downwardstroke being well-controlled, preferably by fixed stops, in such a waythat compression of the tubular element will be very precise and smooth.An initial unit and a final unit of the three-unit assembly of the pumpwill be for completely closing the tubular element, which operates as auniflow valve, and the intermediate unit will be for carrying out thecompression for the metering of the product. Fixing the tube or tubescorresponding to the compression unit will allow possible drawing of thetubes, in order to adjust the metering of each individual action ofcompression. In order to allow a decrease or increase, the meteringtubes can have an initial drawing which can be increased or decreased.

As will be appreciated, the product inlet and outlet valve units can beproduced by any technically appropriate means, production thereofpreferably being by means of a base assembly for receiving the tubularsupply and discharge element and a ramming member to compress the tubeuntil it closes. As is obvious, the tubular elements of the valve unitsmay differ from the tubular metering elements, having appropriateflexibility and being easily changeable. Furthermore, the structure ofthe base and compression ramming member for closing the tubes by jointaction between the two may vary substantially since, although the baseand ramming member may be planar, a curved base and/or pointed orotherwise shaped ramming member can also be used, providing that enoughcompression can be exerted on the tubular element for completethrottling thereof, thereby closing it.

Operation of the pump will be cyclical, actuating in a successivemanner, after the initial filling of the tube, the inlet closure valve,the metering element for partial compression of the metering tubes andthe outlet valve which will allow the pumped quantities to be metered.An electronic assembly will control the metering pump as well asreversing the direction of passage of the products to be metered. Tosimplify assembly, should the conditions necessary for the product allowit (in terms of metered volume, desired accuracy, product features),non-return valve assemblies can be used, advantageously eliminating theneed for synchronisation.

For a better understanding, an embodiment of the present invention isillustrated, by way of an explanatory but not limiting example, in theaccompanying drawings in which:

FIG. 1 shows schematically the basic principle of operation of the pumpaccording to the present invention.

FIG. 2 shows a schematic perspective view of an embodiment, by way ofexample, of the pump according to the present invention.

FIG. 3 shows a front elevation of the pump in FIG. 2.

FIG. 4 shows a plan view of the same pump as in FIG. 2.

Referring to FIG. 1, the pump according to the invention is based on aresilient and flexible tubular element 1, with superior shape memory,which contains the fluid to be metered and is connected at one end to aone-way inlet valve 2 and at the other end to a similarly one-way outletor discharge valve 3, the tube being able to be compressed on the base 4by action of the ramming member 5, which will carry out the fixed butadjustable compression of the tubular element 1, therefore the pumpwhich the present invention discloses is basically based on a flexiblemetering tube with shape memory, which contains the fluid product to bemetered, which allows an action of limited transverse compression to becarried out on said tube in order to discharge the product containedtherein, and this, together with the one-way inlet and outlet valvesystem which will open and close inversely, will allow the completeaforementioned operating cycle to be carried out, i.e. filling of thetube while keeping the outlet valve closed and the inlet valve open, thetubular element recovering its original shape at this stage, followed byanother closing stage of both valves and start of the transversecompression of the tubular element, after which the outlet or dischargevalve opens to allow the desired quantity to be metered. In the pump,the features of the tubular metering elements and those of the valveswill be appropriate for their own operations and the quantity to bemetered can be adjusted by varying the diameter of the metering tube,length of the ramming member and the stroke thereof, i.e. the transversecompression element.

By way of example, an embodiment is shown in the figures, whichimplements the pump according to the present invention. As can be seenin the figures, the pump comprises a central unit 6 for metering andindividual units 7 and 8 for controlling the entry and exit of theproduct to be metered. The metering unit 6 has one or more resilienttubes, only one of which is represented by the numeral 9, arranged overa preferably planar base 10 and a ramming member 11 which is actuated bythe head of the unit 6 by hydraulic, pneumatic, electromagnetic or othermeans. The tubular element or elements 9 will only be compressed inpart, i.e. for the deformation of the tubular element but withoutproducing contact between the internal walls thereof, a further featurebeing that said action of compression has features of great smoothness,which will duly control the speed of the ramming member. On the otherhand, the stroke will be adjustable depending on the quantity to bemetered in each cycle, being fixed between cycles by means of mechanicalstops or by electronically controlling the position of the rammingmember by means of sensors which control movement of the motor usingpulses (encoders).

The tubes 9 will be fixed to the base 10 by means of head pieces such as12 and 13, one of them being fixed and the other displaceable forvarying the length of the tubular element 9, thereby adjusting thequantity to meter both by varying the internal diameter of the openingof the tubular element 9 and by varying the external diameter thereof.

The base 10 receiving the tubular elements 9 will preferably be planarfor greater simplicity, but it is obvious that its shape can be variedproviding that the lower supporting functions of the tube on the base 10and individual compression of each tube are carried out. As is obvious,simultaneous arrangement on the base 10 of tiered forms of the base oreven of the compression member 11 for adapting to different meteringprocesses or diameters of the tubes can also be envisaged when, as iscommon, there are a plurality of metering tubes.

Although not shown in the figures, optionally adjustable fixedmechanical stops adjacent to the base 10 can determine the end of strokeof the ramming member 11. Possible arrangements for controlling theposition by electronic means which can control the movement of the headpiece driving motor by number of pulses (encoding system) are alsoillustrated.

Units 7 and 8 have the function of cyclically closing the tubularelements for the supply and discharge of the product to be metered. Thefigures show a structure similar to the drive unit for metering 6, i.e.with respective bases 14 and 15 and respective ramming members 16 and17. However, it is obvious that said units which act as valves can beformed by other means for compressing the tube, for example, by means ofa punch system to compress the tube and die provided with a shape forreceiving the tube or other valve systems, including types different tothat of compression of tubular elements which have been shown.

Although the element which conveys the product to be metered has beenshown in a tubular form on the whole path of the inlet and outlet unitsas well as the compression unit, it will be appreciated that saidelements can be produced in other types of conduits which are flexibleor otherwise, with the exception of the regions in which they arecontrolled by compression, whether it be in the valve units or in thecompression unit.

Equally, although one tubular compression element 9 is shown, the pumpcan comprise a plurality of tubes to simultaneously meter a plurality ofmicro-receivers, for example, eight, which is the number ofmicro-receivers which are usually arranged in each card for clinicalanalysis.

In the pump according to the present invention, particular care shall betaken that the mechanical forces on the tubular elements, in the case ofboth the compression unit and the valve units if flexible tubularelements are used, are smooth or do not harm the physical integrity ofthe tubular elements, do not reduce the useful life thereof nor harm theintegrity of the molecules of the product to be metered. Thus, forexample, in the tube nipping units which perform the function of valves,deformation of the tube will be controlled so that complete closurethereof is guaranteed, while limiting the deformation of the material ofthe tube so that it does not undergo permanent damage. For example, oneform of adjustment will be that the separation between the externalwalls of the tubular element, after compression, is less than twice thethickness of the tube and that said separation is not smaller than agiven value in order to limit the transverse deformation of the tube,for example, the thickness of the tube itself.

In one specific design, the tubes of the metering part will have thegreatest dimensional accuracy possible, as well as features of shapememory, resilience and flexibility, since the adjustment of the meteringwill take place via longitudinal drawing of the tube. These tubes willeach have, in one specific embodiment, end rings which will allow themto be anchored to the fixed and moving anchors which are indicated. Thespeed at which the product contained in the tubular element isdischarged can be adjusted by regulating the speed of the compressionramming member. The frequency of the metering can also be adjusted tothe desired value.

The assembly of controls, sensors and adjustments of the pump areincorporated in an electronic assembly thereof, which is notillustrated.

The present invention is described by way of example on the basis of theembodiment shown, which does not have to be considered as limiting. Onthe contrary, all the variations which can be introduced into the pumpaccording to the present invention by experts in the art with knowledgeof the present invention will have to be considered included in thefield thereof if they do not exceed the scope of the accompanyingclaims. Application of the pump according to the present invention canalso be variable, extending to applications other than filling analysiscards.

1. A tubular pump for metering liquids, comprising: a resilient andflexible tubular element, with shape memory, for receiving a product tobe metered and which is capable of receiving an action of limitedcompression of the walls thereof; a ramming member for imparting theaction of limited compression of the walls of the tubular element; andrespective valves situated before and after a region of the tubularelement that is compressed by the ramming member to control a supply anddischarge of the product.
 2. A tubular pump according to claim 1,wherein the tubular element is compressed in a direction transverse toits longitudinal axis.
 3. A tubular pump according to claim 1, whereinthe tubular element is compressed without there being contact betweeninternal walls of the tubular element.
 4. A tubular pump according toclaim 1, wherein the quantity of product that is metered is adjusted byvarying at least one of an external diameter and an internal diameter ofthe tubular element.
 5. A tubular pump according to claim 4, wherein thediameter of the tubular element is varied by longitudinal drawingthereof.
 6. A tubular pump according to claim 1, wherein the quantity ofproduct that is metered is adjusted by varying a transverse stroke ofthe ramming member.
 7. A tubular pump according to claim 1, wherein thequantity to be metered is adjusted by varying the length of the rammingmember.
 8. A tubular pump according to claim 1, wherein the tubularelement is filled due to resilient expansion by recovery of its shapewhen compression ceases with one of the valves being an inlet valve thatis open and the other valve being an outlet valve that is closed.
 9. Atubular pump according to claim 1, wherein one of the valves is an inletvalve and the other valve is an outlet valve and the valves are capableof selectively switching between a first state with both the inlet andoutlet valves being closed when compression begins, and a second statewith the inlet valve closed and the outlet valve open after compressionbegins and continues until compression ends.
 10. A tubular pumpaccording to claim 1, wherein a stroke of the ramming member forcompressing the tubular element is limited in an adjustable manner byfixed stops.
 11. A tubular pump according to claim 1, wherein a strokeof the ramming member for compressing the tubular element is determinedby position sensors which are adjusted by a driving motor pulse count.12. A tubular pump according to claim 1, wherein the ramming member isoperated by means of a hydraulic cylinder assembly.
 13. A tubular pumpaccording to claim 1, wherein the ramming member is operated by means ofelectromagnets.
 14. A tubular pump according to claim 1, wherein thetubular element is compressed by mechanical means combined with positioncontrollers by a coding system and corresponding step-by-step motors.15. A tubular pump according to claim 1, wherein a speed at which theramming member actuates is adjustable.
 16. A tubular pump according toclaim 1, wherein the frequency at which the product is metered isadjustable.
 17. A tubular pump according to claim 1, wherein the valvesand the ramming member are synchronized by means of an electronic unitwhich is incorporated into the pump.
 18. A tubular pump according toclaim 17, wherein the electronic unit is capable of adjusting operatingparameters of the pump to regulate a discharge rate, metering frequencyand volume to be metered.
 19. A tubular pump according to claim 1,wherein the valves are valves for compressing flexible tubes which makecomplete throttling of the flexible tubes possible, in order to reachthe closed valve position.
 20. A tubular pump according to claim 1,further comprising a plurality of separate tubular elements, arranged ona single base and which receive the compressing action from the rammingmember.
 21. A tubular pump according to claim 20, further comprising aplurality of ramming members to compress different tubular elements. 22.A tubular pump according to claim 1, wherein the tubular elementconsists of a single part from an initial point of entry of the liquidto a last point of filling of a receiver.
 23. Use of the pump accordingto claim 1 for filling the micro-receivers of clinical analysis cards.